textproduct: Rapid City

KEY MESSAGES

-Showers and storms will shift east and end this evening

-Blocking pattern will support a ridge of high pressure over the CONUS this weekend into next week, supporting very hot temperatures and elevated fire weather concerns

-Thunderstorms will be possible at times this weekend into next week as monsoon impulses advect around the ridge and into the region

DISCUSSION

(This Evening Through Thursday) Issued at 1232 PM MDT Thu Jul 23 2026

Upper level ridge over the Rockies will shift east and expand over the central CONUS. This will result in very hot temperatures this weekend into next week. Departing batch of monsoon moisture will support scattered showers and storms into the evening as diurnal heating allows for expansion in coverage this afternoon. Locally heavy rainfall will be possible given high PWATs and slow movement. Upper ridge will begin to shift east Friday although a ridge topping impulse will shift a trough across the southern Canada and the Dakotas, with the tail end of the trough stalling in the FA later tomorrow. Much warmer temps tomorrow with highs in the 90s most places, with a few low 100s possible in areas on the Plains. Aforementioned upper trough may support a few isolated showers or storms across NW SD in the afternoon, carried a low pop for this. Separate weak impulse may also support a shower or storm across northeast WY in the evening and so have also added low pops there as well. Upper ridge will shift east Sat with very hot temps expected. Highs will reach 100 or higher for most locations on the Plains, supporting adv level heat index readings. Low level moisture will deplete some with mixing, but sustained southerly flow will prevent the BL from drying out too much most places. This will help keep heat index readings higher, esp over central SD. Heat looks to persist at least through Tues, possibly longer depending on how passing ridge periphery impulses affect the ridge. Expect that there will be TS chances at times in this period as monsoon moisture advects around the NW side of the ridge. This includes Sat when another monsoon wave will advect around the ridge in SW flow and into the FA later Sat, supporting high based TS chances. Gusty winds will be possible with any thunderstorms in this period given high based nature and near inverted-V profiles. Ridge will retrograde back west some by mid next week, supporting slightly cooler but still hot temps, with expected TS chances as the lee trough interacts will passing impulses.

AVIATION

(For the 18Z TAFS Through 18Z Friday) Issued At 1117 AM MDT Thu Jul 23 2026

VFR conditions are generally at expected at the TAF sites through the period. Isolated to scattered showers and storms will be moving through this afternoon and early evening. Localized MVFR conditions may be possible in heavier rainfall.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.